Personal details belonging to more than 13 million Korean gamers has been leaked after one of the country’s leading video game developers had its database hacked into earlier this month, according to a report from The Korea Times.

Nexon, the marker of Maple Story, a game with 100 million users from across more than 50 countries, immediately alerted its users of the breach, advising them to change passwords after names, resident registration numbers and passwords were obtained. International user data was reportedly left unaffected while no financial transactions details or bank account numbers were accessed, according to the Korea Communications Commission (KCC).

The KCC and Korean police are leading an investigation into the incident as a spokesperson from the organisation confirmed:

We have set up an investigation team, comprising of experts in private information and security, to get further details.

The KCC is also assessing how culpable Nexus is for the breach, which is yet another incident of user data being compromised on a large scale.

Chinese hackers have been linked with a number of attacks this year. A report from Symantec suggested that more than 48 US firms were targeted as part of a six month cyber espionage campaign waged out of the country, while the Japanese government was a victim of Chinese attackers in October.